1. Field of the Invention
The present invention relates to missile control systems and more particularly to a jet tab actuator system for a thrust vector control coupled to an aerodynamic surface control system.
2. Description of the Prior Art
Thrust vector control jet tabs have been utilized to enhance reaction jet, aerodynamic surface or other forms of attitude control for rocket propelled vehicles, such as missiles. During initial flight of an earth-launched rocket vehicle, the aerodynamic surfaces of the vehicle may have limited effectiveness in controlling the vehicle path. The aerodynamic surface effect may be enhanced by incorporating individual reaction motors in the tail surface control panels, as in the Maudal U.S. Pat. No. 4,044,970, assigned to the assignee of the present invention, or by directing propulsion engine exhaust against the control panels as in U.S. Pat. Nos. 3,286,956 of Nitikman, 3,276,376 of Cubbison et al, 3,013,494 of Chanut or 3,164,338 of Cooper et al.
In some cases, during vehicular travel at such altitudes and speeds at which significant control surface aerodynamic effects occur, such control may be adequate. However, at high altitudes where aerodynamic effects are reduced by low atmospheric density, attitude control may desirably be enhanced or may be available only by thrust vector control.
One method to vector thrust for control of missile flight utilizes thrust control jet tabs which are inserted into the missile exhaust flow to deflect the exhaust and thus provide control moments. Such tabs are effective for inducing pitch and yaw attitude control. However, jet tabs are ineffective in inducing roll torque. For roll control, reliance can be placed on aerodynamic surfaces because aerodynamic tail panel forces are adequate for roll attitude control above altitutes at which aerodynamic pitch and yaw attitude control is lost.
Conventional thrust vector control tab actuator systems employ separately powered actuators independent of the actuators for the movable aerodynamic surfaces. In such systems pitch, yaw and roll commands are provided to the aerodynamic control surface actuators; pitch and yaw commands are provided to the thrust vector control jet jabs. Thus at least two separate sets of actuators are required, thereby increasing the complexity and weight of the missile.
Examples of systems utilizing jet tabs or vanes in addition to aerodynamic control surfaces may be found in U.S. Pat. Nos. 2,969,017 of Kershner, 3,139,033 of Geissler et al, 3,188,958 of Burke et al, 3,776,490 of Weis, and 3,986,683 of Ellison. Other systems for controlling missile flight by resort to reaction jet forces may be found in U.S. Pat. Nos. 2,995,319 of Kershner et al, 3,136,250 of Humphrey, 3,637,167 of Froming et al, and 3,764,091 of Crowhurst.